Presently, the process of manufacturing cementitious products such as tiles in small individual moulds remains substantially the same as production methods that have been employed for the past 50 years and is still popular throughout the world.
However, over the past twenty years, the production of tiles has developed resulting in tiles with a greater contemporary appearance in response to the fashion and trends of modern architecture and interior design.
Presently, commercially available cementitious slab products are produced from a mix which typically comprises cement, silica sand, large (or coarse) aggregate pieces, a water reducing admixture and water. The large aggregate pieces are included to make up mass and may vary in size from approximately 3 mm to 10 mm or larger. Stone chips are often used as large aggregate pieces. The water reducing admixture may be a plasticizer based on Polycarboxylatic Ether Polymer.
The strength of material used in tile production has increased in relatively recent times, allowing tiles to be produced from a single large and thin slab, similar to marble or granite slabs, which can be cut to produce square or rectangular tiles of a desired size.
Large slabs are formed in individual moulds which are then subject to a vibration process. This causes the finest particles to move to the bottom of the mould. A slab takes the form or shape of the surface of the mould. This is known as “off-form” material.
Such production methods have allowed for greater flexibility in variation of sizes and thicknesses of square and/or rectangular tiles. Cutting tiles from a single slab allows for the production of square and/or rectangular tiles of differing sizes, which would previously have been produced in small individual moulds. Flexibility in production allows tiles to be made to a size at the request of a client without significant re-tooling or maintaining a large number of different mould sizes in stock. Additionally, precision machinery allows for a more accurate and superior finishing for the tiles.
In addition to the abovementioned advantages, cutting a large slab into smaller tiles takes advantage of the inherent natural aesthetic qualities of the large format slab. When separated, the smaller tiles have a unique appearance which increases the visual appeal of large surfaces such as walls and floors when covered with the smaller tiles
After the material is mixed it is placed into large moulds where the mix is vibrated into place. For mixes where fluid is added in order to activate the bonding process, the mix is poured into the mould and allowed to cure to a sufficient extent to allow the slab to be removed from the mould. For dry mixes where the bonding process is commenced by subjecting the mix to heat, the mix is poured and pressed into the mould. Dry mixes usually include resins that have a relatively high melting point and once sufficient heat is applied, the resin melts and bonds the remaining materials in the dry mix together. Cooling the material in the mould then sets the liquefied resin and allows the slab to be extracted from the mould.
The moulds are generally stored in a location where the material is allowed to set and harden prior to cutting. The storage period for wet mixed slabs is approximately one to four weeks before the slab is sufficiently cured for cutting of the material.
For naturally cured large slabs, once hardened sufficiently they are de-moulded and stacked for curing. Curing may require up to 4 weeks depending on the method and effectiveness of the curing process.
Of course, the need to allow the slab material sufficient time to cure prior to the cutting process requires the poured slabs to be shifted from the pouring line to a storage area. Generally, the slabs rest on frames after removal from their mould and are packaged for curing. This requires an interruption to the manufacturing process and the provision of sufficient storage space to store the slabs for curing in addition to the manually intensive processes associated with the removal of the slabs from their moulds and placing into storage for curing.
Slabs are calibrated for thickness before being cut into tiles. Following cutting, tiles are “rectified” to produce more accurate sides, the edges of the tiles are chamfered or arrised to erase chipping damage that is usually caused during the cutting process. Individual tiles are then processed including cleaning, drying and packing before being dispatched for sale.
The cutting process and subsequent operations are commonly performed on a continuous automated production line.
As a result, cement or concrete tiles may be ordered and installed in a similar manner to marble, granite and/or porcelain tiles. Further, tiles processed in this manner generally result in a higher quality installation outcome.
However, present production methods of tiles have a number of significant problems.
For example, the processing (cutting, calibrating, arising and/or rectification) of a slab is generally effected by use of diamond cutting tools, such as cutting blades, calibrating tools etc.
When cutting a slab, which is a very hard material, the edges of the cut are subject to varying degrees of chipping and rough edges. Further, the slabs and/or tiles are liable to crack or break during the cutting and calibrating process. The stresses can cause chips and breakages, particularly at corners where the cementitious slab or the tiles are weakest. The chipping, cracking and/or breakages can result in wastage or the need to repair damaged material. This can be both costly and time consuming.
Another disadvantage is that the processing is difficult and requires care by skilled operators in order to ameliorate wastage due to chips, cracks and/or breakages. Such skilled operators are costly and the production of the tiles from the slab is time consuming and interrupts the production process.
Subsequent to the calibrating and cutting process, the slab products are generally stored again to fully cure which may require a further three to four weeks of storage in a controlled environment before dispatching the products to their installation destination. The further storage of slab products for final curing represents additional handling and storage costs.
Other disadvantages in present production techniques include the need for expensive equipment for cutting (including diamond tools and large capital equipment), large energy costs (for example, electricity) and a large amount of water, which is consumed during the processing of slabs into products. It is not unusual for a calibrating apparatus to cost $400,000 or more with a cutting line expected to cost approximately $700,000 to $1 million dollars.
The cutting and calibration processes also result in a large quantity of waste material, which is created when material is removed during the cutting and calibration processes. The waste must then be separated from the water used for the processing prior to re-use of that water. The separated waste material must be collected, treated and disposed of, which may be inconvenient and/or expensive. In this regard, the cost of a water filtration system is expected to be approximately $100,000 to $200,000. Further, the operational cost with respect to electrical energy consumption of all the equipment is generally significant as most of the equipment needs a multi-purpose power supply.
The cutting process can be particularly wasteful when cutting small tiles or mosaic pieces as the diamond cutting blade removes approximately 3mm to 5mm of material from each cut. When producing many tiles from slabs, the total volume of material removed during the cutting process is significant.
As a result of problems with existing processes, it has been considered that producing small tiles, mosaic pieces and tiles with curved or other non-quadrangular shapes is too problematic. In the case of mosaics, present production methods typically result in approximately 50% to 60% wastage of material thereby only generating a 40% to 50% yield. This is primarily due to the substantial amount of material that is wasted as a result of the cutting process producing relatively small tiles combined with the increased incidence of damage inflicted on the tiles. Unfortunately, the relatively small size of the tile leads to an increased incidence of chipping as the tile moves and vibrates as it is separated from the slab as compared with larger tiles that are not as susceptible to movement during separation due to their greater weight.
Furthermore, cutting other types of slab material, such as plasterboard, can be problematic as such materials are generally cut in a hardened state subsequent to manufacture. Typically, preparing a factory for production of slabs and tiles is an expensive undertaking requiring a great deal of planning, preparation, construction and installation time. A factory floor must be specially adapted in order to accommodate heavy purpose built equipment, with each plant requiring drainage systems and effluent tanks for collecting, separating and treating waste material from the water. In addition to all of the abovementioned disadvantages, the construction of a factory with special purpose drainage systems in itself represents a significant cost and hence an impediment to the establishment of a manufacturing facility.
Tiles produced by present processes are not suitable for applications such as creating mosaics, countertops, kitchen islands and/or furniture etc due to the rough edges and/or appearance of the large aggregate pieces at the sides or at the surface of the tiles. Currently, it is preferred to use other materials which are considered less problematic for these applications.
At least one further disadvantage exists with present slab and tile production, being that the products have a high flexural strength. The high flexural strength has the disadvantage that cracks in the tiles do not appear readily and may only become obvious after the product has been fixed in place. This may lead to the requirement for expensive replacement of products such as installed tiles.
Cracks do not readily appear in the product even in circumstances where the product has suffered a solid impact. Such cracks do not readily appear as the interlocking structures of the coarse aggregate pieces tend to hold the material of the product together.
An alternative product to slabs and tiles produced therefrom is natural stone material. However, natural stone material has many variables which are difficult to control. The stone material may be too soft, too hard, too porous or may have too many veins to be useful for a particular purpose. Furthermore, such materials may not be aesthetically appealing for a customer or suitable for a particular application.
It is an object of the present invention to provide a process and product which at least ameliorates one or more of the above-mentioned disadvantages associated with slab and tile production.
The reference to any prior art or prior art techniques, in this specification is not, and should not be taken as, an acknowledgement or any suggestion that these references form part of the common general knowledge of persons skilled in the relevant field of technology of the invention as claimed herein.